The invention relates generally to electrical machines and in particular, to a ripple spring used in an electrical machine.
Armature windings, also known as stator bar windings, are routinely inspected in electrical power generators, to verify their operation. In some generators, a stator yoke in the generator surrounds an armature core and partially encloses the armature windings. The stator windings are formed from a plurality of copper conductors that are wound in the armature to form loops. The armature windings may be arranged within a stator slot in such a manner that the generator may maintain desired voltage and current characteristics during operation.
Typically, a generator includes a wedge system with ripple springs, to induce a radial or circumferential retaining force to the stator from wedges or ripple springs to facilitate reducing movement of the stator bar windings within the stator slot. However, if the wedge system itself becomes loose or the ripple springs malfunction (e.g., crack), the amount of retaining force is reduced such that the stator bar windings may vibrate during operation. Over time, the relative motion of the stator bar windings cause damage to the insulation surrounding the stator bars and a potential stator bar winding failure may be caused through electrical shorts to ground.